摘要
根据地震反射特征，万安盆地地震剖面由上而下识别出Ｔ１、Ｔ２、Ｔ３、Ｔ３＾１、Ｔ４、Ｔ５、Ｔｇ共７个地震反射界面。结合区域地层与钻井剖面资料，以Ｔ３、Ｔ５为界，由上而下将盆地的新生代沉积层序划分为Ｉ、Ⅱ、Ⅲ三个超层序。超层序Ⅲ由Ｆ（Ｔ５－Ｔｇ）层序组构成，为盆地初始发育阶段扭张构造应力产生的地堑内形成的层序，分布局限，其体系域展布特征不明。超层序Ⅱ由Ｄ（Ｔ３－Ｔ４），Ｅ（Ｔ４－Ｔ５）两个层序组组成，
Seven seismic reflective boundaries (T_1、 T_2、 T_3~1、 T^ T_4、 T_5 and T_g) from up to low are recognized in the seismic profiles of Wan'an basin based on the analysis of seismic re- flective features. Synthesized the regional strata and well-log information, the Ⅰ 、Ⅱ and Ⅲ supersequences bordered by T_3、 T_5 and T_g are divided for the sedimentary beds formed in Cenozoic times. Supersequence Ⅲ consists of sequence member F (T_5-T_g) distributed in grabens or half-grabens and formed by transtensional stress during the initial stage of the basin developing. Its spread area is smaller and its tract patterns are riot clear. Supersequence Ⅱ consists of sequence member E (T_4-T_5) and D (T_3-T_4) formed mainly in basin's depression stage. During this period, Wan' an basin experienced the following evolution stages: continen- tal lacustrine basin, bay basin, offshore and shallow marine basin. Among them, sequence member E is formed in a transition period between rift basin and depression basin. The first set of important resource rock occurs in sequence E_2 and E_1. Sequence member D formed in the basin's depression stage and the second set of important resource rock occurs in it. Superse- quence I is made up of A (T_0-T_1), B (T_1-T_2) and C (T_2-T_3) sequence members, it mainly formed in the basin's wholly subsidence stage, the regional cap rock of Wan' an basin occurs in sequence B_5 and B_4 of the sequence Member B.
出处
《南海地质研究》
1997年第9期67-77,共11页
Gresearch of Eological South China Sea
